Typical prior art sensing edges generally include a sheath having a cavity along the length thereof wherein at least a portion of a switch is located. The sensing edge is attached to an edge of a door which may be moved in different directions. When external pressure is applied to the sheath of the sensing edge the switch means is activated to actuate a door control device which causes the door to either stop moving or open. For example, external pressure may be applied to the sheath when the sheath contacts an obstructing article, such as a body of a person, located between the sensing edge and an opposed surface. By stopping or changing the direction of movement of the door, damage to the obstructing article may be prevented.
Prior art sensing edges generally have a switch located within a cavity extending along the length of the sheath, the cavity being sealed at both ends. The interior of the cavity typically includes first and second electrically conductive contacts positioned on opposed foam layers within the cavity and spaced apart from each other. When the sensing edge contacts an obstructing article, the portion of the sheath contacting the obstructing article is deflected to cause the first and second contacts to engage and make electrical contact therebetween to actuate the door controlling device.
Such prior art sensing edges are typically time-consuming and difficult to assemble because the foam layers, contacts and electrical wiring must be inserted into and secured within the cavity and the contacts and wiring must be connected. It would be advantageous to have a sensing edge which may be assembled during formation of the sheath and fastening device and wherein the switch (electrical contacts and connective wiring) may be located within the sheath cavity while the sheath and fastening device are formed.
It would also be advantageous to have a plurality of elongated cavities which extend along substantially the entire length of the sheath to increase the structural integrity of the sheath and ensure that the first and second contacts engage upon application of a force to the exterior of the sheath. Such internal cavities would provide channels through which electrical wires and other components may be routed or positioned for attachment to the first and second contacts. The interior cavities would also protect the electrical contacts and wiring from moisture and vapor and prevent dirt and contaminating foreign matter from damaging the electrical contacts and wiring contained therein. The cavities could also be used to house control circuits and/or end of the line resistors.